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BIO122 Final Exam

Terms in this set (34)

sign stimulus
External sensory stimulus that triggers a fixed action pattern.
pheromone
substance secreted by organisms that influences the behavior of other members of the same species
altruism
unselfish regard for the welfare of others
inclusive fitness
reproductive success of an organism plus the fitness of its close kin


direct fitness + indirect fitness
kin selection
Natural selection that favors altruistic behaviors by enhancing reproductive success of relatives.
population density
Number of individuals per unit area
population dispersion
General pattern in which the members of a population are arranged throughout its habitat.
population demography
study of vital statistics of a population and how they change over time
cohort
a group of people from a given time period
survivorship curve
Graph showing the number of survivors in different age groups for a particular species.
exponential population growth
The geometric increase of a population as it grows in an ideal, unlimited environment.
logistic population growth
Population growth that levels off as population size approaches carrying capacity.
carrying capacity
Largest number of individuals of a population that a environment can support
life history
Traits that affect an organism's schedule of reproduction and survival.
density dependence
survival or reproduction decreases as population density increases
metapopulations
groups of populations linked by immigration and emigration
ecosystem
A biological community of interacting organisms and their physical environment.
detritivore
organism that feeds on plant and animal remains and other dead matter
detritus
Nonliving organic maters such as remains of dead organisms, feces, fallen leaves, dead wood.
limiting nutrient
single essential nutrient that limits productivity in an ecosystem
nitrogen fixation
Process of converting nitrogen gas into ammonia
ammonification
decomposers convert organic waste into ammonia
nitrification
ammonia is converted to nitrate ions
denitrification
process by which bacteria convert nitrates into nitrogen gas
primary production
Amount of light energy converted to chemical energy by autotrophs.
secondary production
Amount of chemical energy in consumers' food that is converted to new biomass.
production efficiency
The fraction of energy stored in food that was not used for cell respiration.
trophic efficiency
Percentage of production transferred from one trophic level to the next.
competitive exclusion
Strong competition can lead to local elimination of one of the species.
ecological niche
Sum total of a species' use of the biotic and abiotic resources.
realized niche
the range of abiotic and biotic conditions under which a species actually lives
resource partitioning
Differentiation of niches that enables similar species to coexist.
character displacement
evolution of anatomical differences that reduce competition between similar species
trophic structure
Feeding relationships between organisms in a community.
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